Cover Letter Clunkers to Avoid on Your Job Search

In fact, 91% of hiring managers consider cover letters "valuable" when vetting potential employees, according to a study last year from OfficeTeam. Another 79% say they expect cover letters with resumes from people applying for a job, even though many resumes are now sent online.

"Although the job application process has increasingly moved online, the importance of a cover letter shouldn't be underestimated," says Robert Hosking, executive director of OfficeTeam. "It often is the first opportunity to make a positive impression on hiring managers. It's also a chance to provide context for your resume, expand on key accomplishments and explain reasons for employment gaps or career changes."

Problems can start right up top on a cover letter, and often roll right through the rest of the document. Here are five of the biggest mistakes job applicants make when creating and submitting one:

Not taking instructions. Human resource managers are sticklers about following directions. If you can't handle the details, such as including a job requisition number in the email subject line or listing your salary requirements, your resume and cover letter may well be the first eliminated. Another tip: Address the hiring manager by name (and not by "To whom it may concern"). If you don't know the manager's name, call the firm and ask, or check the company's website.

Going on too long. Legendary author Ernest Hemingway once said brevity was key to his literary success, and he was rumored to have won a bet that he could write a story in six words (his entry: "For sale: Baby shoes. Never worn.") Cover letter writers could learn from his example: Keep the letter to a single page. Hiring managers are busy and won't read a lengthy monologue on your life and career. Stick to the facts, and your accomplishments, in an organized fashion.

Mirroring your resume. Too often, human resources managers, as the gatekeepers of a company's hiring machine, will toss a cover letter because they see it as just a reproduction of your resume. There is a difference between the documents. A resume is a timeline of your career and accomplishments and a good cover letter amplifies that resume, giving you some room to elaborate on your accomplishments, explain gaps in employment and tailor your accomplishments to a specific employer's needs.

No "hook" up top. If, in the very first paragraph of your cover letter, you don't show what you bring to the table, don't expect a hiring manager to keep on reading. It could be something as straightforward as this: "As a 15-year veteran of the medical software industry with two key industry awards, I'd like to offer my credentials for your surgical instruments marketing director position." The goal is to keep the hiring manager reading, and then picking up the phone or emailing you when they're done. The more descriptive you can be, and the more you "bring to the table," the better your chances of standing out from the crowd.

Going "generic." The cover letters headed for the circular file are certainly the boilerplate ones that make no effort to identify your interest in the specific company you're pursuing. That can be remedied with research you can use to show your understanding of the company and its products, services and financial performance. A visit to the company's website, or to a financial website that tracks the companies you're applying to should give you enough nuggets of data to sprinkle through your cover letter to grab the hiring manager's attention.

Also, make sure your contact information is accurate and up to date. Include any social media handles (such as your Twitter address) to boost the ways a manager can get in touch with you.

Writing and presenting a good cover letter is about making a case for you as a good match for the firm. That's what the firm's managers expect. And if you don't provide it someone else will.